Telephone switching offices and companies using a large number of communication devices such as modems, telephones, facsimile machines and the like are all faced with the problem of interconnecting these devices with electrical and/or optical cables. Such cables frequently reside within ducts or troughs that contain a large number of similar cables. Each cable terminates in a plug to facilitate the interconnection process. As devices are replaced, or as new interconnections are required, these cables need to be removed from the duct and replaced by others. And while adding cables to a duct is not a particularly difficult task, removing them is. Indeed, removal is accomplished by disconnecting the plug from the communication device and pulling it backwards (i.e., by its associated cable) through the duct. Since it is not desirable to sever the plug from the cable, the plug needs to be streamlined in order to avoid snagging other cables as it is pulled. Imagine, for example, the difficulty associated with pulling a plug, shaped like a fishhook, through a maze of wires; and yet the most popular plug used in the communication industry is shaped that way. (Perhaps the most widely used and accepted are know as "RJ-type" plugs which are used on all telephones and disclosed in numerous patents including U.S. Pat. No. 3,860,316 to Edwin C. Hardesty.) These plugs have achieved overwhelming acceptance by customers because they are inexpensive, operate reliably, and their operation is intuitively understood.
RJ-type plugs include a locking tab (hereinafter "cantilever latch"or "latch") for interlocking with an associated jack; but the latch snags other wires and cables when being pulled backwards through a concentrated area of wires and cables as though it were designed for this nefarious purpose. This difficulty is exacerbated by the fact that the use of such modular plugs is growing (such plugs are now designed to accommodate high speed electrical data communication). Today, even optical plugs are being designed in this same general style.
To some extent, the "snagging" problem has been overcome by including a pair of sloped sidewalls at the back end of the plug. This feature is commercially available from AT&T in its "Snagless RJ-45 Plug," and is incidentally shown in U.S. Pat. No. 4,611,875. However, such sidewalls need to be taller than the free end of the latch, which must be deflected downward in order to release the plug from an associated receptacle. Since the sidewalls are relatively close together, it is difficult to manually operate the latch.
In communication equipment, it is frequently desirable to make connection with a pair of individual transmission media and to be sure that they are correctly positioned. For example, one transmission medium may be used for transmitting data while the other is used for receiving data. In optical systems, precision alignment is critical and it is customary to use specially designed connectors for aligning each optical fiber. Nevertheless the desire for customer convenience has led to the development of duplex optical connectors which include two optical fibers and the means for aligning same. For example, U.S. Pat. No. 4,787,706 discloses a duplex optical fiber connector for terminating a cable containing a pair of buffered optical fibers--each held within a fiber-holding assembly comprising a ferrule and a spring-loaded base member The fiber-holding assemblies are contained within a common housing that is formed to include two flexible molded plastic sidearm members for interlocking with a mating receptacle. The housing includes details which can be used for assuring polarization during interconnection with another optical fiber connector. And while this connector provides excellent performance, it requires its own family of connecting apparatus and does not interconnect with apparatus designed for unitary (simplex) connectors.
U.S. Pat. No. 4,953,929 discloses a duplex connector which is constructed by joining two simplex connectors together. However, the simplex connectors shown are not RJ-type, and if they were, there would be a snagging problem.
What is needed, and seemingly, what is unavailable in the prior art, is a duplex connector which is constructed from a pair of RJ-type simplex connectors, and which resists snagging when pulled backwards through a concentrated area of wires and cables. Desirably, this duplex connector should be inexpensive, easy to assemble, and easy to manually operate when installed in a dense array of similar connectors.